I’ll be the first to admit that I haven’t really figured out how to get magic to happen on the flow bench with B1 heads.

I think I’ve only tested one set that had what I thought had really good exhaust flow..... and my recollection is they were huge(run on a 572 with spray).

This is more like what I see......
Some older bowl ported heads, mild “full” porting on the exhaust.

On the intakes I opened the bowls up and tweaked the short turns.
On the exhaust the primary thing I did was to narrow up the guide boss...... which was more work than it should have been for what I gained.

As rec’d:

Lift———in/ex
.100——75.6/53.6
.200——149.2/112.2
.300——220.8/165.9
.400——282.3/209.8
.500——336.6/236.2
.600——374.5/242.6
.700——371.7/241.9
.800——352.1/241.9

After rework:
Lift———in/ex
.100——73.7/54.2
.200——148.8/115.9
.300——219.6/165.9
.400——284.2/212.2
.500——338.4/245.7
.600——375.6/257.8
.700——408.0/258.9
.800——400.8/258.9

The thing with the ex flow is, you only need what you need, and blowing out the size of the port chasing a number on the flow bench isn’t likely going to get the car down the track quicker.

I guess the questions I’d ask are, what are the goals/expectations out of the build?
It would seem the OP must be pretty far off from where he wants to be if the motor was still running fine and he elected to remove it and pull it all apart rather than tweak on the combo in the car.